The present disclosure relates to tape drives, and more specifically, to roller bearing variance.
Typically, in a tape drive, there are multiple roller bearings, or rollers, of the same general size, but are not rotating in perfect synchronous motion with each other. The roller bearings are also slightly different in diameter, usually at a microscopic scale which may cause positional variance of the tape with respect to the read/write head of the tape drive.
The runout characteristic of each roller bearing is unique. The runout describes how each roller bearing contributes to the Position Error Signal (PES) during typical track following operations. The runout is the tendency of the roller bearing to deviate from a nominal rolling motion, e.g., a wobble. The runout of a roller bearing may cause the tape to vibrate off-track.